The present invention relates generally to machines for processing objects, for example printing machines including a turret, which can rotate about its axis and which carries a plurality of object-carriers radially at its periphery via supports which are in turn rotatably mounted on the turret, and a plurality of workstations distributed circumferentially around the turret, in line with the trajectory of the object-carriers, and some of which are printing stations while others are processing stations, for example drying, varnishing, flame treatment, dust removal or other stations.
The printing machines are used to print circular objects, for example, such as flexible tubes made of synthetic or other materials and to be printed with several different colours in succession; in this case the object-carriers are cylindrical mandrels onto which the objects are threaded.
Feeder systems are of course provided for feeding the object-carriers with the objects.
Until now the feeder systems have included a finger, generally of cylindrical shape, reciprocating along its axis and adapted to push each object directly towards an object-carrier.
Although these systems operate well, they nevertheless have the disadvantage that, to access the next object to be pushed, the finger must be retracted by a distance at least equal to the length of the object, and that it is only after this movement, which frees the space for the next object, that the next object can take up its place.
The subject matter of the present invention is a feeder system in which the next object to be pushed takes up its place before the finger has effected its retraction stroke, which increases the feed rate.
In accordance with the invention, a feeder system for feeding objects to object-carriers of a machine for processing the objects, in particular a printing machine, said system including a reciprocating finger for pushing each object directly towards an object-carrier to place the object on said object-carrier, is characterised in that said finger is carried by a reciprocating carriage slidably mounted on a chassis and is rotatably mounted on said carriage so that it can occupy at least an operational position in which it can push an object when it is moved and a retracted position in which it can avoid an object when it is moved.
Said finger is advantageously also subjected to the action of spring means which urge it towards its retracted position and locking means are provided for temporarily retaining the finger in its operational position against the action of the spring means.
The finger is preferably fastened to a shaft rotatably mounted on the carriage and the spring means comprise a spiral spring wound around said shaft.
The locking means advantageously comprise a plunger mounted to slide in a direction orthogonal to the rotation axis of the finger.
In the position of the plunger in which the shaft is locked relative to the carriage the outside surface of the plunger preferably cooperates with a flat surface formed on the shaft.
The plunger advantageously has a peripheral groove which in the position in which the shaft is unlocked is in line with said flat surface.
The carriage preferably reciprocates between two abutments carried by the chassis.
The plunger is advantageously adapted to cooperate with the abutment in its locking position and with the abutment in its unlocking position, the carriage being in line with said abutments in each of those positions.
The finger preferably includes an operational position selector ramp adapted to cooperate with a fixed roller carried by the chassis.
The invention also provides a machine, in particular a printing machine, including object-carriers and a feeder system for feeding the object-carriers with objects, characterised in that the feeder system is a system as defined above.
The objects are advantageously carried by an inclined table.
The objects are preferably retained by a rim of the table and the rim is parallel to the rotation axis of the finger.
Said finger is advantageously generally C-shaped and straddles said rim.